Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The annotation readOnlyHint=true already covers the safety profile. The description adds that it returns matching routes with IDs, which is a basic behavioral trait. It does not disclose other behaviors like pagination, result ordering, or error handling, and since annotations already declare read-only, the description is not heavily burdened. A score of 3 reflects adequate but not rich behavioral context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is two sentences, front-loaded with the core purpose ('Search for routes by name or number') followed by a concise usage note. There is zero waste and every word adds value. It is efficiently structured.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's simplicity (2 params, clear output schema exists), the description covers the essential context: the tool resolves a short name to an ID and pairs with specific follow-up tools. It does not explain the output format, but that is provided by the output schema. The description is complete for an agent to decide when and how to use it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so both parameters are already well documented. The description adds a concrete example '44' and mentions 'route short name', which are also present in the schema. It does not provide new semantic meaning beyond the schema, so the baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states the verb 'Search' and the resource 'routes by name or number', and it clearly indicates the purpose: to resolve a route short name to a route ID for further lookups. However, it does not explicitly differentiate from the sibling tool 'onebusaway_find_routes', which may overlap in function. It is specific and actionable, but lacks explicit sibling differentiation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides explicit guidance on when to use this tool: 'Use to resolve a route short name (e.g. "44") to a route ID for schedule or vehicle lookups'. It names the downstream tools (onebusaway_get_vehicles, onebusaway_get_schedule_for_route) that benefit from this resolution. However, it does not mention when not to use it or present alternatives such as find_routes, so it falls short of a 5.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.